1. Field of the Invention
The present invention relates to an inner surface shape measuring apparatus and more specifically to an inner surface shape measuring apparatus which performs measurement by using a light-section method.
Priority is claimed on Japanese Patent Application No. 2013-016611, filed Jan. 31, 2013, the contents of which are incorporated herein by reference.
2. Description of Related Art
Conventionally, for the purpose of measuring the inner surface shape of a tested object, an inner surface shape measuring apparatus that performs measurement by using a light-section method has been used. For example, a radially spreading planar luminous flux is projected toward the entire circumference of the peripheral wall surface of a tested object having a tubular internal space, whereby a ring-shaped light-section line is produced over a circumferential direction on the peripheral wall surface. An apparatus is known in which it is possible to seek the inner surface shape of a tested object in a predetermined coordinate system by detecting the position of a light-section line on an image obtained by imaging the light-section line.
In Japanese Patent No. 2862715, there is described a planar luminous flux projecting apparatus for light-section measurement (hereinafter simply referred to as a “light projecting apparatus”) used to perform such inner surface shape measurement. The light projecting apparatus includes a light source, an optical device which makes a luminous flux from the light source direct forward, and a conical reflecting minor which performs direction conversion of the luminous flux, thereby projecting the luminous flux as a radially spreading planar luminous flux.